MEN OF MATHEMATICS
ing, but slowly enough to remain homogeneous and for the
rotation to be the same in all its parts.
'At first very approximately a sphere, the figure of this mass
mil become an ellipsoid of revolution which will flatten more
and more, then, at a certain moment, it will be transformed into
an ellipsoid with three unequal axes. Later, the figure will cease
to be an ellipsoid and will become pear-shaped until at last the
mass, hollowing out more and more at its "waist", will separate
into two distinct and unequal bodies.
'The preceding hypothesis certainly cannot be applied to the
solar system. Some astronomers have thought that it might be
true for certain double stars and that double stars of the type
of Beta Lyrae might present transitional forms analogous to
those we have spoken of.*
He then goes on to suggest an application to Saturn's rings,
and he claims to have proved that the rings can be stable only
if their density exceeds 1/16 that of Saturn. It may be remarked
that these questions were not considered as fully settled as late
as 1935. In particular a more drastic mathematical attack on
poor old Saturn seemed to show that he had not been completely
vanquished by the great mathematicians, including Clerk
Maxwell, who have been firing away at him off and on for the
past seventy years.
Once more we must leave the banquet having barely tasted
anything and pass on to Poincar^'s voluminous work in mathe-
matical physics. Here his luck was not so good. To have cashed
in on his magnificent talents he should have been born thirty
years later or have lived twenty years longer. He had the mis-
fortune to be in his prime just when physics had reached one of
its recurrent periods of senility, and lie was so thoroughly
saturated with nineteenth-century theories when physics began
to recover its youth - after Planck, in 1900, and Einstein, in
1905, had performed the difficult and delicate operation of
endowing the decrepit wu4 with its first pair of new glands -
that he had barely time to digest the miracle before his death
in 1912* All his mature life Poincare" seemed to absorb know-
ledge through his pores without a conscious effort. Like Cayley,
he was not only a prolific creator but also a profoundly erudite
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